Germ cell tumors (GCT) of the testis are the most common cancers of young men 15–35 years of age. Although relatively uncommon overall, their incidence has doubled over the past 40 years. Since the introduction of platinum-based combination regimens, the majority of patients with this disease are now cured.

Natural history

The majority (> 90%) of GCTs arise in the testis. Less common primary sites include the mediastinum, retroperitoneum, and the pineal/suprasellar region. Cryptorchism (the incomplete descent of one or both testes) is a well-defined risk factor for the development of this disease and the surgical correction of this problem (orchiopexy) performed prior to puberty reduces the risk for tumor development. Additional well-defined risk factors include a prior history of GCT and genetic syndromes including Klinefelter's and Down's syndromes.

Germ cell tumors can be divided by histologic type into seminomas (30%) and nonseminomatous germ cell tumors (NSGCT). Nonseminoma tumors may include any combination of the embryonal, endodermal sinus, choriocarcinoma, and teratoma histologies. A seminomatous component may also be present. The serum tumor markers human chorionic gonadotropin (HCG) and alpha-fetoprotein (AFP) are often elevated in patients with either nonseminoma or seminoma, though elevated AFP is found only in patients with NSGCT and confirms the presence of a nonseminomatous component.

Pattern of spread and recurrence

The classic presentation of a testicular GCT is a painless scrotal mass though this finding occurs in only a minority of patients.